The cleanup of acid gasses, such as CO2, from natural gas has been an extensively practiced technology. The industrial removal of CO2 from natural gas dates back to the 1930's. While several technologies exist for the removal of acid gasses, one of the most commonly employed practices is the use of aqueous amines. In this process the amine reacts with the CO2 to form a carbamate or bicarbonate salt along with a protonated amine to balance the overall charge. The overall process for a thermal swing absorption process is depicted in FIG. 1. Here, the liquid, CO2 rich amine from the bottom of the absorber, is then passed through a heat exchanger to improve efficiency before being heated to a higher temperature in the stripper. The stripper removes the CO2 as a gas from the amine solution to produce a lean, or CO2 deficient solution. The lean solution is returned to the absorber by way of the heat exchanger to repeat the process.
The application of CO2 capture to post-combustion flue gas separation has recently been an area of major concern. On the long term, it is thought that this technology will be critical to reducing emissions from fossil fuel combustion potentially responsible for climate change. Thus, the market for carbon capture technologies could be enormous with over 1.5 billion tons of CO2 produced annually from coal combustion in the US alone. In the shorter term Enhanced Oil Recovery (EOR) and utilization in downstream products (polymers or chemicals) represents a significant opportunity for marketing technical solutions. The total market for post-combustion CO2 capture technologies (>$6B over the next 20 y) represents massive potential value for intellectual property development sales such as from technology development or licensing fees.
With continued societal and regulatory concern over the global climate change, the market has been driving the post-combustion capture technology development towards commercial scale. However, the technology is still in principle inefficient and energy intensive. One challenge is that the flue gas from fossil fuel boilers is at near atmospheric pressure and the concentration of CO2 is relatively low at 12-14%, thus, huge gas flow rate and large scale of absorber would cause high capital cost. Another technical hurdle is the energy penalty associated with the CO2 capture and solvent regeneration which could generally reduce a pulverized coal plant's output by around 30%, which equates to a very significant 60-80% increase in the electricity cost.